Python aiogram bot: send message from another thread - python-3.x

Question

The telegram bot I'm making can execute a function that takes a few minutes to process and I'd like to be able to continue to use the bot while it's processing the function.
I'm using aiogram, asyncio and I tried using Python threading to make this possible.
The code I currently have is:
import asyncio
from queue import Queue
from threading import Thread
import time
import logging
from aiogram import Bot, types
from aiogram.types.message import ContentType
from aiogram.contrib.middlewares.logging import LoggingMiddleware
from aiogram.contrib.fsm_storage.memory import MemoryStorage
from aiogram.dispatcher import Dispatcher, FSMContext
from aiogram.utils.executor import start_webhook
from aiogram.types import InputFile
...
loop = asyncio.get_event_loop()
bot = Bot(token=BOT_TOKEN, loop=loop)
dp = Dispatcher(bot, storage=MemoryStorage())
dp.middleware.setup(LoggingMiddleware())
task_queue = Queue()
...
async def send_result(id):
logging.warning("entered send_result function")
image_res = InputFile(path_or_bytesio="images/result/res.jpg")
await bot.send_photo(id, image_res, FINISHED_MESSAGE)
def queue_processing():
while True:
if not task_queue.empty():
task = task_queue.get()
if task["type"] == "nst":
nst.run(task["style"], task["content"])
send_fut = asyncio.run_coroutine_threadsafe(send_result(task['id']), loop)
send_fut.result()
task_queue.task_done()
time.sleep(2)
if __name__ == "__main__":
executor_images = Thread(target=queue_processing, args=())
executor_images.start()
start_webhook(
dispatcher=dp,
webhook_path=WEBHOOK_PATH,
skip_updates=False,
on_startup=on_startup,
host=WEBAPP_HOST,
port=WEBAPP_PORT,
)
So I'm trying to setup a separate thread that's running a loop that is processing a queue of slow tasks thus allowing to continue chatting with the bot in the meantime and which would send the result message (image) to the chat after it's finished with a task.
However, this doesn't work. My friend came up with this solution while doing a similar task about a year ago, and it does work in his bot, but it doesn't seem to work in mine.
Judging by logs, it never even enters the send_result function, because the warning never comes through. The second thread does work properly though and the result image is saved and is located in its assigned path by the time nst.run finishes working.
I tried A LOT of different things and I'm very puzzled why this solution doesn't work for me because it does work with another bot. For example, I tried using asyncio.create_task instead of asyncio.run_coroutine_threadsafe, but to no avail.
To my understanding, you don't need to pass a loop to aiogram's Bot or Dispatcher anymore, but in that case I don't know how to send a task to the main thread from the second one.
Versions I'm using: aiogram 2.18, asyncio 3.4.3, Python 3.9.10.

Answer 1

Solved, the issue was that you can't access the bot's loop directly (with bot.loop or dp.loop) even if you pass your own asyncio loop to the bot or the dispatcher.
So the solution was to access the main thread's loop by using asyncio.get_event_loop() (which returns currently running loop, if there's one) from within one of the message handlers, because the loop is running at this point, and pass it to asyncio.run_coroutine_threadsafe (I used the "task" dictionary for that) like this: asyncio.run_coroutine_threadsafe(send_result(task['id']), task['loop']).